One reason why Andrew Marvell and other poets of his period offer many different perspectives and often contradictory views on love has to do with the nature of poetry as a genre. A poem is not a philosophical treatise, and needs not strive towards the coherence of an essay or proof. Instead, poems often reflect the confused and contradictory nature of human experiences of love, which can indeed be a mixture of physical attraction with spiritual or intellectual harmony. Another issue is that from Marvell's point of view, human mortality limits our knowledge:

But at my back I always hearTime's winged chariot hurrying near;And yonder all before us lieDeserts of vast eternity.

Thus rather than being able to experience a complete and whole love, like that of God for Creation, or angels for God, human love is by its nature fragmented and limited.

I also added, that Renaissance puts emphasis on the individual love, physical and spiritual elements of romantic love. Poets in the Renaissance could deal with issues that were taboo in the medieval age, it was acceptable to develope a romantic relationship that is highly idealized.